SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '350932a32dc45bbb28059072201df55ae138772c40807a1a7a9ecb66aed24cb5' 
  AND token = '+3acW1ki5tNlPl0H/G7GLz7xHIU3f07ze0Qt2ZtYjpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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