SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aa52823a998d88f683060b2c9655b545204991e0608f3022d03bdd87bfca7336' 
  AND token = 'Ck2zIUx4zjBSKOoMuhihADBxqLHajOsIY1/JX6yUUK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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