SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38a8b626aeafc122ba0f2686d474313aea71ce3ed633e9d6b17a6cc3546febf2' 
  AND token = 'nzHL98VKaZagcC5KAzJcHkwI+T+EqhWr1WUfhnVCwes=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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