SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2a421698aab835ffae0dc9cededc7c9301cca869e5bbf5758acf74bbbb51d60b' 
  AND token = 'YDGBhJtmQp/VJdcvx4c3WofSW/Dq+GqhfyNeU3Qec1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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