SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de324335a466158fecaf290af5ae776556f5809850ed4acc2da80ddb6d043470' 
  AND token = 'mQBs7RZRWX5kBeWzS+BXLJg3NKE1xL1IdTIVKiGQqDA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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