SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fec3f9559d102248fa225e41c4333a115a38c8b17422abdf4790b16a077b2bef' 
  AND token = '89PQLcxfj2ykLOUkKJdXTUxktvKsMSquzbe8KvzIiZY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}