SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7735f43c34b1ed36f10d8b35ce97e3b11bbb9f26140aa974d18e88b55558088a' 
  AND token = '8wzLNaDP1tn8Z+8tTxYFVGwzYOfkVlhgllJQc/igQkY=' 
  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"
    }
  }
}