SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e7f7a1fce8d368b92153bd32851c231cc1d09907499b121d9ae7c8c5784bc13d' 
  AND token = '5FlrzdJCKAFL6wKHfwmFpGu7ZlDZrllGX2Z1vxSVjBQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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