SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ab16faff1b040f31320b1d0fb2c14b11309a759db3a9808d549263b8a814a3c' 
  AND token = 'rcBTKD5+6/zV58X8npXBPDgUYPUsvGB9cuZ+ZO+sx80=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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