SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e836581a98af5d69440068e64ddf3e1211b9bca02de11a89c77c00a9fc732197' 
  AND token = 'YzdfARJI1nyDEM1vKWOxrk233TdtPfKOwF1tWFY6gms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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