SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8549245e7086084e304a1c06a241c248b40a79a69cd197cb6108af770029048f' 
  AND token = 'SAnEaTkx8fY92WFIIS4rN/Z8NVUouWsvLLgDKyx4bZ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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