SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9529b0cc1103c8652c8766fd6a5dca374cca1f3d1e46d292686a52737f5316ef' 
  AND token = 'S1KVqj/BJJN0/USujCAzGzr3SWPQ9OPJSuujazH0uyI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}