SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '55c0f19cf3619c23bee2f10349253f798d503074fb4dc182615fb55e0a888d0f' 
  AND token = '6wZmKowjlJhM87yRkNpbB48WXaBdt3eYJDGYIpKhAuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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