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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8dfe1849a936510a994d4543a81bb3cce5508fb5db93f6929b5a8ddf532a0ffb' 
  AND token = 'D2UfDv8kfzvhsQZoL9mKkMTjcaj7cArBM/zS4BFvW30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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