SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '30864c1e0dfd3c7edeaebfbe68cb08968a23100c1962eefea2e063a2ee3c9b91' 
  AND token = '/RDnxj+KWH1yTfTv21HmJVTHVSUGekD7YB6VZycI2PM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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