SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9408fb8dbfcfcee7143505d44a43b93643eae77d2e1f3108bd726ec8e9b1f79c' 
  AND token = 'TxKOTFB4mecMMkCH4meZrxLc6QPRKpr3a+Z5HM41BPM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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