SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4073cb5978f919a9346497bb54bbcb0522d3995b34ab6139f24693d50127a4d6' 
  AND token = 'w4FVPgQE2Ol6PhpBPTRlrx6YiRrUNrDs5mkm9nSKtUM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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