SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'db48960920927d98924c21e220475b474e8fbdce03bb644afc0af98d26d79abc' 
  AND token = 'gR5VtQlNcONxfADJrUT/kTppuwdZfDkOeWr31Wmc/s4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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