SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c968265423aab85b9182d0bccb16007d79a4d3c59c186f1f595ac55f89c906b' 
  AND token = 'y/AsIIYgHjv4S8SDtS+hUh15KYnmD/4vIOUTlZxFVek=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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