SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4c5c11c1793b7e02f27bbea8fa4134fd9781c5011a56a34f622095cd9475f103' 
  AND token = '1KCsJUyRwlmUMdUjPwMa5jIpqDLBZdIXwc68/BWRHKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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