SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2c47a0dbef7192471c3ec82fac97825d50b790b22aff4ffe701aa91ff5e30e8d' 
  AND token = '+i/6mRjVagkcrPCqvcWh7amFIOnRwecIzgEnqRZQb4A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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