SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '553c559037186d2f76017d53963051c6ecf87617e24a3cc09ea4f780311f56f9' 
  AND token = 'QpP0VVphioVSb1CGXWxytExofHczHFULaCczgeQcdwk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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