SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '968ca8f2385b173e19081b1d16884b95c976b28cbd509a490a2e9f81fdc57db7' 
  AND token = 'jw8rzjl+2RuZlq5nu80yg1+839zkRx2xk+s9JjYs2wk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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