SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb5c8f76a3cb725bd55ef6adcbc96f0fe1d9b455ece1a4110f559c057a9eba85' 
  AND token = 'Lwp6mtGBzMmyqe+VQ7GnsZAk1N/1yfeYhlL8vJXj4Sw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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