SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18fef809d748ae18ef5af04110eacfd22d9ca3afa58fd00802a3c4ff043ed977' 
  AND token = 'rRVIC4z8c0PfeMwJpi9rJEAcaG95SKfSkVUeKSIG/C0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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