SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '515f999b39bd88477477de3a55bceb15c9556ee6108b1f6c4325159d2b57f444' 
  AND token = 'pfOB/LfGwEbAozYyLe0PWa+jWc8sg2R6i0C+alZLXKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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