SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f0d2c35c15c21ab4d23e53b92bd736c0c52373ede42f2928a5546feb1585a3b1' 
  AND token = 'xdrEQ71bFPXqeG65WpZ3YmO3A5uoeRZ1pz1iDjRbs3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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