SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b4d8d92c176839b6ef0d0d933e57c15d5fc133d7f6a5465044127927269ee71' 
  AND token = 'PimXSOowCRm+9neF2pZp9VmCArVua/LW3jEpZaHPzpI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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