SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd9e0375cfb0ece29f74b5afd6a07fc4a7f668b90a4c90911fccd5c4b113a3fc8' 
  AND token = 'ioj7RFzMG1ArXoD7Ac4Oo9uH+PMvfY196N2lD1BvATM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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