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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a1188e2b57d52e0587b85b00c002133f319ccbaa00575fd293cc755b0fb45a94' 
  AND token = 'MUjQal//L68IyEmr86ikLM8Vjl1rTOvIdzjWl5dUD7Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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