SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a834d629079d887a275338e8ce704a8d13123b8d25d199719f7f1cc74038838c' 
  AND token = '1jGAyQnw6LXeYtqIZHZis+XtT3NLfVgQCSgovbeutGA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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