SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5423bda653f32fbace5cbdef165e4bb0825eb1d115bc34008ac00dd85f28cf65' 
  AND token = '3HqC42yOTqsmrxBoH/7uN4362pqoqN6sPjknFtcBmoo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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