SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c8bec317278a68ec5b90356e732f51da9d9d89b25111573517269626f745560a' 
  AND token = 'eBL/8+oCSwdMCebm4Ehx7a+VXgRmBm6HO89o+smPhyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}