SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '20b2d361793f580b93373758a081814f37a610f81ab1f72dfbd23944412c48e6' 
  AND token = 'sqTjo8slTiL0skKXJ34Xgc3HPo2J0VVMwYiyQ2eDhQs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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