SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '928794826c5297184415dadb1109699056ef5048b76a4c222016b0306eee8608' 
  AND token = 'VljBpCqc9EmilbsymnPzON0NyE9q5J2XmGsVWJmXqDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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