SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b33be606b6eb72cd4d95b39578e85b47f0f7bcb14faf8884ba1b68617c7c6216' 
  AND token = 'CkYrv0iG4r+b5IiAVbmRiEo93kAWh3MFw+h/VtjezvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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