SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '49a7ec6b70681aa1a8e296a8322fb20819f532ac69e81848bf55239f041f0c76' 
  AND token = 'pUd1IF6YhrCBUPrOzSMX1I6UqZ4L5MVx8leqK+xoxQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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