SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8534d17fee204e2dfedbf17d8a617573c5f9978f6acf8f3b12945667fc2c21f2' 
  AND token = 'vCC3k+Dq0+6bI8YIV1hcYoU0liXDAFpy9JdYuJtjz+g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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