SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '32b1c1e0a75f1a38a8a0768f6a979d369247301d533954abdadcfa0920282a5f' 
  AND token = 'PchvpViXVLtGSW4+Sa1MNjXJBD/Y86NUnlAr+hS0vfw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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