SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8a2a733f69ebdd830b1d9610a382a69b799e9ce8230ce62044e3edade0c3c121' 
  AND token = 'I1kFDpNYEPTIzmlrL0Fbk1eqdqYFnhrEOPSz/CEVlAM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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