SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67613036d72fbdcddaef43d3fa9be8f02700e8c29d0d48790bd5cd7c40045813' 
  AND token = 'PMbrnU6DaFAEEiVQ14oKAn4M9KcL2ndv+sBSwyD/AMc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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