SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd5d07fc8f379ee2882ab98424621c172f71e9d3b10cd444e07a4f7f566c4291' 
  AND token = 'mnZ10yZAvnQjkSZmUwCw2JLiFSEQmi6ieenD0Sr1Zo0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}