SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '305308d475057268dd6eb8dfe5a0278d7b73617965f925b44f05ceb8ea66c853' 
  AND token = 'stBwQ7XQ/ZmGwl1h5snzhQGRYhBBoukcGJVpTHHEn7U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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