SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd1a34820dfb8ce76567cac719d3a67b2b202ff12d5e07bac1b0178b9b4dde40a' 
  AND token = 'mjoVYpzkoHWqxJdWMiFGpjuuK7q/LvJRWvUFpshlQpY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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