SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7884ec35d3c0e4a4f2f56f1f19e89a5575e8910eb6f8e21abfada2f75660e39c' 
  AND token = 'yBYKBDGDIADd6Hk8mVV+CIlzcsqyaQkwrluaxUlXpwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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