SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d99143ad8940070d0f644e2850ee7a7f73e303a2c81a700ef5b5e4d1a36b0aa' 
  AND token = 'OXtCuJHz1Jvemd+Ka7DYLVznbwwsqLBj5oqgFU1eHCo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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