SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51602dbedf058bfa967d1be957b618420aa78e1c63f2bf75ae74ec811ed558ff' 
  AND token = '1O3RgwbXBOLgdwit0eCeJl36RcnlprDLczgOpisCl1I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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