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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4bde7b75ee6cddfea5d8aa3f50b72df943a49405147bec1ef86d41404e5c6c7' 
  AND token = 'ExoYTzYr5xfpueqY4sUBXWU0FwsYhqfOjqHTgbK/Jb8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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