SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b6fc35c4bbb55610d52bbfb98574dab8666b4270d29209111e2a05cc8453cb8a' 
  AND token = '8zNW8uPG9jnOfHjMucEqvXOkAJSL1SQR7Bs9nMhnyUo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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