SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd3ed500ebeca04e639cd62b63b841a510795dc0032e5cd716f7105b0845b78e4' 
  AND token = 'wAU2uNQet3ClaXnvA2izrqsYaG6rlKEbOkf6LotTIb4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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