SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29e769ad4c042b84619e50269bbc3a0b7b6b61bbe789323fbb388b12d5b6f790' 
  AND token = 'Qf65qRL0207A7kWvvRj5DpngmYtgqgzwHhJRStgVm+s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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