SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '156186663e1bd3f998fa3e1803a6e56654f224267d807894b6d16cd5f839da34' 
  AND token = '9r8YGVkaaLuuCUzgftVBu0+nwIkYCZsghld+EEP/DzI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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