SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f2c37d74c29600e0919017abb97e142e5c9edfacb6dab2ce1eed292021b75b29' 
  AND token = 'aVRsS8mIDLMjSnJw+kl8pbQb7QOLQntOBYCx8E+xWKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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