SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68363cb2314a551d0c79e658d0baabe09253c9c02726c9149ae5291de5472f90' 
  AND token = '/ffhRSLzR2vntr+V2KBqVBU6EzBvC/CzaK65OVqDIXk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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