SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '424d6b4c91a0aa220a8418eae68a827e891d0781cf34a8f2ba31b3eb51f1fded' 
  AND token = 'jelCL/uKwyY3gskd18cCwaf+MN6kCYgFWZ9Kr8VdCe4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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