SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '661f335deffee7ebb1f7691d5eab481cc3372f3dd2c6f1b9ec92509ee71f9f8f' 
  AND token = 'JaJYF4qPOxSNBSwkdjA6HKxYNmF/mLjPai+bVGqTLYI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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