SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2e1cf3d43aa8b84a5c699d6c57ef422b7af3eb523fdc9aaf5838ac90a96af5f6' 
  AND token = 'j9mvJ27X+v883b+G8bjfi2cUyXElx1pOIqXsIhwhuFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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