SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb1a72715bfd2847a40ddee740c9e86eaa502a35e58b51a65f50a69014b03d70' 
  AND token = 'eGdNXE4KGOpYVB5XiupKZ1F2/NoaqJvvuVCBWkGj52E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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