SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'af6f886b5ce05f42de0b9b0ec21778f36d9bfd0a6fa27998b05ad2461abb64d8' 
  AND token = 'xcvd0iZFiKBLPxFfZNl/pvZLyyoOq+KyJZuW/BZWULc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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