SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '25c7129eb69303ddf11c2fa224f1a510c6d72ecde7adf05538b3ea13ba062689' 
  AND token = 'xd6tcntwbkyS+TvShs28LObBQdjEIkRKV8bpcS9qHGU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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