SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ebd778320e813d56e438f149c07e19999f4234de7bb357035f0165cd44d10339' 
  AND token = '5LibjHLVegTzpSnxyniIwq8msHVh+y1lg8rc2efrdoc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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