SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a97304bc5032ad2c05963d5b859ef823e5f91b8442e14fb9fa480755938b868e' 
  AND token = 'H4PwwUN4eg85JacQ7nS86b6k/n05hBAGUWrAgrYczk4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

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