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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c357068593d3d1b53ad42f08bde4c5ce495f3cd2ab2069813b24c054c1605543' 
  AND token = 'nIEBlAk1Mb3vQfRyfBSPTfVaAo1CM92RzdaeqgYOrmA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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