SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '284d98edb2b5b0a26e7b1407acd4f6ce68bd6e1b519a6aaa5fbe637e22455b39' 
  AND token = 'cJ2aEy9RrsA7qaz2vmDLNKm87sPjxAzDz03h+p+1ATo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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