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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb7e5146294bf06f25a6efa7af7b3ebcaebd1d20dbc899df83ad915bc833e91c' 
  AND token = '+n/xD8f5EiIGIE4S/hdUrpZIA9dKlIUd8tRWzh2NexI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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