SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18e78862985b90fb3f4f45fbc3b72c5a727f03d54f4281209c31a46756a87ac7' 
  AND token = 'k5a19O9PYKelxVbTc3nLda91Na5Q/cHIwprbcxunw1w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}