SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '495050dc46e57808ce3519596019db541c243b397d9d0c47642baf5e81a4f150' 
  AND token = 'ZrCOXENYAn9q/ZUcBzCaTI0mottSQ7HzKzWLIu23CoU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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