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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5e230aaa367159a3e9635699f6c9f2f0bbb4dd4cc4ccc0970c601c2d72b1947' 
  AND token = 'c2emyoNhL8BYzfQInvlLf8mFfbo/NoZULGo+yuj/FZg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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