SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e156423a04cefec93240bab79354987a2f551cee6661a4528a05da3adc044867' 
  AND token = 'gySDUBCfEjkRKenBY5/L8fuxfpNjGeDv+li/NGc+yyU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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