SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c12f658c44bfc64113944fabb38618a22af905a31b82fab24c91fedaa3d591a' 
  AND token = 'hiSXHun+Nna4KmwJwqeNI5fedDMXZf69tcSXneksTgw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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