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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e8f7c366f7cdf98b5e39aada5130d9b2fdd873d8b3452f52aa45eaa715bfa2b2' 
  AND token = 'ydWrSuVceZMV3Oxai41HiQfLAgtx+e3Uu5xtOKM2GP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}