SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4bbe5ded62bf03ea386b564ed1f8bcc049eee4edb3821265d28ee27d751a246' 
  AND token = 'x2jSQmHlkUEwthBwKW0oCVNZhFjx0lvh8f3t2sLMwN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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