SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '291d6dfcdd23c7bbca25ceb13b73fb1ed93dd5fad2be80fe6c000f58d3bec165' 
  AND token = '5LjpLFmTGOoFHV8dlSD3TohlCuwzdOwQ1gayUy7Q+Xc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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