SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aff178d9d75187870cbd26c1dc68f32da8c738304e5d8e0d42b243ea403dd849' 
  AND token = '6BdYpuUC+Co8yF75nOUzOswkZwzvZjjJJVriJujB99o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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