SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5977dcde6951ff9f61a4bb757e0a8856fa73e699738242defa8652f6e7c2a850' 
  AND token = 'r5IJze8Kl4jVTBIXi4HbiBSpbwOyJ7JDYGHB922WGh8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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