SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4da5f19e4c11863784ec5c6287f72af86273436d05c7d9d23df24f2b08566892' 
  AND token = 'l+PYjkTPVF5XqSOl/JzwGnFk1e+Ry8TRjUmRp0WuI+E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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