SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52808f2c223788cafe1443a64694345e66cfd2788e168d95b0f9ed5b79904775' 
  AND token = 'JE1iOMteHtaDjoYoptCaydWW1zhj+WtCSsL/KyrMVn4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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