SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9869fcaf3362c6987da839e2894c84df3a1db1bc1ffa8c379ad67e8257256936' 
  AND token = 'Lr1Wl8mdBXJ32znIEoCdjUDHuFac4ebaZCJyGrroGl8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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