SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '85c46eec087181804dde10e252221ce4a399bdb966f8681c2467879c630a8e2a' 
  AND token = 'Tr6pte1a+yZlw8u2ejNhyPzF90uJj7G8FoGV3d2zC/w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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