SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9eb4450d913a9498c13ae5026bd6c347687b8c252bc608da85a9003729288a2' 
  AND token = 'csgGQfRgPdXmI+STkFGrpSNoN6Gw/n9GfjCJKnh9WHA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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