SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42c8366755acd25ffe19f309285c4617db05b5d8df3a5f68fe1bc9fa50574999' 
  AND token = 'IEBo8pVRi4vQtDo2Gd2XgAz/CS73RPoBKkVQaEZ/p7I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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