SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dff3fde5cb1a6472cc806c06884395b9593f51c1d5c902a7f369794d690982bd' 
  AND token = 'bfDAYdkVYpu2t1vY1YYi1ZZKjgNEftCB+vTKAaRbYPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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