SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76b80860bdcf445e74f66701a1d41a4a2e6d30351328f29895083d5b8fef5902' 
  AND token = '8J6a+n9QPgJWyz/7Y3j0I94uN/wrBoIJO0UEQX3FOwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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