SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7eab9505379020bb9796dae1c4db97166d692054eff81e135e2e9a1cbbf9a01d' 
  AND token = 'RhaTPI6yj+7LTxBovpHhOQJppoRvKrELCWueMKaP2vM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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