SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae1b820234820217300640fb5bed3041fc4ee77ae7108c2720c060e8a560bb9c' 
  AND token = '/Du/ggrDRHJEBoBO4v641w2UxQcx7baa7oNoUsgyMAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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