SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7fcb19cb08df2b7396501d08c4027a447896c496416a4f4ebefa36a6875d3ff' 
  AND token = 'zfvGybVsqlP14mTrNHiFPq39jrmTTHkkTDzQEX0Totk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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