SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '769d50827ee51960d04155d08126a60da40325c64d50b283b7e3e18d0e980452' 
  AND token = 'KuRSqvAiNyYQaTcAxj7xrw+s8nywxNstuj5KdourznA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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