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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc552dcfd6d55c3791aa6138752e4b31a8e144345ce589b0cfd761b87c6b2235' 
  AND token = 'jc8/bR/Ds5c3vTfzHq7mbjOeltiBGQxHQBnI1xqXMCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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