SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '257750f276e60d4bca3e2ba2d92109b765581b1a1bd34d112e313975ee609ecf' 
  AND token = 'CjYkRDv1Rjnht4LPhnoKohMQyIIChfuUY7Bk+goXw5M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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