SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5eca1f55d600a33b264e4809c62a645f96fbd7a8ab7a07e4213f2fdefcb11a40' 
  AND token = 'lMSn2T8+0CLUvQY74M0qnZTcOVC42RxyTeWb/Dcq3bI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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