SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a736cf379824cc88c17204847f634ec370f9b4aa0a0fac126594d358b9460657' 
  AND token = 'F4vpcpAg8TjCZ+UhfNenEvP4l48Idk3tedR2uhmtfUE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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