SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f129d64b7f801fbda519ef1f8ad868e5aa377c50da157535140c524b552297bb' 
  AND token = '8T6yhD7OU2bVJSJ5u7H6lstAr842tzI1ih5y/nTk7pM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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