SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98c66b27f00d4fb22d497aeaf3471546791aba7d5844e69e608b0b278121e6a0' 
  AND token = 'rQT804E4YB43OuSejZejSovq8zF529z7lgY7coussQA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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