SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'ec503280ecdff546496eede5c29fae4ea5076052d6767e663c3131f12840c876' 
  AND token = 'J0dT61oHQA2XSpPSs/4mnm5rA1u4XdVNa2p9hA1z7iA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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