SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e0eaceb003c5456052aad3962e247d9bf41ea0a87fa60e99a1e260f924d2e03' 
  AND token = 'F0qr8vLLvF07dUfr0nZaHbBFa4sBRU5sPwKElfETz7k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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