SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd7290d11d10fc37057ba37f2c149d14a62cea733a8e7a1c3a9fd2896e1bd4db8' 
  AND token = '6xrBBntq5WStHowkEVeErJiBhT0DpQRZ5eLMDDM6OII=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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