SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '139848b6326f4df87c614709e423f796aa9db2bd59567f7c47fb163bcdac44fd' 
  AND token = 'BTRHQnNEh/dUAABvfCkbCTP9osyBGAAZZHCpayMNbak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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