SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '728a42c6b0d905e813eac1c9b725c6adef4969abceaf9f69a807b5acc5cf352b' 
  AND token = '86e1TGJIpAETivelxGU8OGzGYlXvosA9hzvvsLlcs/A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}