SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c755b0bc8181e09ffc8a2a53f7d16ef45e254055a6bff6d174d896a5349ce47' 
  AND token = 'dWKSDqFWDlsDUDx7ne87V9FmfCj5GcYDYMmm9MoL8iM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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