SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cd67c918c71230f919bcbc6093eb244bd48185156dfe49720f5128eb22a89571' 
  AND token = 'euSTdGycpZYB01FDYKcVs+YpJ64j0t71ZUZMUiunpUY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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