SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '67188c5a050a942e93f8236b61cc6c3537bd0feafbac179e404d771ddc81705a' 
  AND token = 'K2iH2tyNs43ouMPKcytKDYW3dlOTearK7AyTdlIzq4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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