SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a5a1fbcdb3f291750400652f075658b3242bd83aad37314dd8f543c29d9e00e' 
  AND token = '03VCn8+vUUqoi92wrnBzMbrnWcAkReNILLUHXhlB8Cc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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