SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5855baa5f893772643eedf6607021cc506c5137ccdf17f4c0163741783a9dec' 
  AND token = 'kCRS8zqcdfzNuh1nCHwou3tqRV+Af0cTKKc2prsTgjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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