SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8c1c24f1fa22efc0fb5538c797b4df8566e320ef7ad0edb39cdb36da28406aab' 
  AND token = 'dh3KHAInuhbvRrb0YUCFyFXowwLJr/s7lznqSxMh71E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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