SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5bc21cd93f964bf772e22ef8223948e45ab2ad832d620cf631cdf188cd7184db' 
  AND token = 'UlQSLZOUrPAmKmu78lQgq2b2pL9UzKIW9+V4tIWVkIw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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