SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e294c0c90e2e2ec711d3a5bbf117bdcf88a9475636616d47b776e1a06fc8ede6' 
  AND token = '6vQkFrQFBkA1XiPVyrBBcvf7HQN3k11+kSi7w9YCbRA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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