SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8b3dac1131ad75c3465dc452dcfc28a095b05f8493b37e2f0d1f80430ee26350' 
  AND token = 'fbwmCZEST/lSc1w3YmATuzyNBW+SJk9DAMdIRuIPeWY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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