SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd88a031be3510af43ca76611457fbb27543db5bcfea1cd2cfea6a143f818a25' 
  AND token = 'O0r7qbe9uYUJnMPk2z6FORBJPOalukaKNcVPVCYPboI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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