SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b5788825fdbd066f69615c7fcfc6a5412fc94e2658278146c1fe5aaca3b89e2' 
  AND token = 'RjpD+sLUvpwNF7IPvGBF8YmaMczxETGdlIEXe81G4Rk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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