SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = 'e2473d5703f9b1ab7cdf0dbb728300b0227be9b6e506a961f0ad8f0984e492cf' 
  AND token = 'SzOnoo6tsLQ26qP0F1tUBCzl79P0JecHuM9nZJJj+lw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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