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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e39923a8a67ac3dd862ece54823fa39844fdddf6b2a8f637cd764cb6e1e3cf5e' 
  AND token = 'tEXXnvu2Fk0Ow1ezrSuJ/zxWIm0+fEEuSPr2UiVVdjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}