SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21bb630c1fc952c40c269870ffd1536061648d097b8f3b1a5af16ae58ef78e9a' 
  AND token = 'hE9qa93Yu70jZKNlKOusO6RIPbvdUdwld/dESEOil34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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