SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76bcf30c9fb229afed7de8735dd8766c957829eabde229440941f8dec8eb1979' 
  AND token = 'Kd7hgXKlFaKtUd7mVLqaG6NJ0M3bjAthpgWK06ywJ2A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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