SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9bddb22bef86acf02af0146a20618884752d1c0346f6cf6155835540c8098a80' 
  AND token = 'c8Qu0BmIXmO1p5dGsBJN2IShT5UB3lq/muRq1u2qkwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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