SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ac781e74b6975e6a070629ee6ce7fb90fef51da038360b6eb60704266dae12c' 
  AND token = '8unf1rWp2uxoblxVlDTGpkcdp0sRvrgxH76LR7u20dk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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