SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2517f2a7facdd60df5d3e14d3f5424015d5c2bb8e73032f1a0b8c4fbb4941e6' 
  AND token = '5+OM7CJwZXhjpQ7XqzB4Fd7JWeuWqjTDKq8LYTN97J0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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