SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '35125dfe888b52a089863338ec2349cd61c1c4c2ba5b68add16ff203b02c54f9' 
  AND token = 'US3wRv/ksteS1aknUu1VvC8ityX/aDHs/TixiAU76e4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}