SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52dec6ff9e42673a8df3e886ea6def5387ce3c0b57858377aa461b7794e3b9e6' 
  AND token = 'qAtI3ti1rfsM2a755PoxDWxcNYoxBIhnDKSx/vfO4f0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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