SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '879a228a0e1e80b63804d3a3ac97861d966a53d4a0b8533c8be54a9fd22ce146' 
  AND token = 'AOYheDd2JMZ/2sNd8K0RjzzPxkETUSVJj53YU0t61r4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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