SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ae5249a17c63656539221c907f81c28f80e115ec9d25cc9babaa6346f679bfd' 
  AND token = 'TilrPjK7efDqAm/Y38Nx2KmnCrLWoJrzUBsjI63Ojv8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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