SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f957063f50c164adf8da547e0f842681fd89ea28d336cde9ee4c8f933993f3a' 
  AND token = 'rzl2Ab48ti1cIE2ChgwMEGJ7QozRNWbNpiWcioLiUko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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