SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'df1ccb97f4eff3f125c05aa587ce924cf49d47a60be4f8fbb3f5d3b68dd6d252' 
  AND token = 'rxnqmnwlVwQU/cdoKzEgZqqMS3Zwz8NpNsFTPFqIv8k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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