SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76f4044e33053d1cf7a81f3f13c3c677bdad2e654ff8963f0a8aee9b24623706' 
  AND token = 'A/sWn2fgIDqqL2gjmQ0lCvJa4+h0jLX5PsUZLlYatAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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