SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2503a8b316a5e6424ccc80e90bcd45e73e76c5d205c56aa5abbe9ab78a85694b' 
  AND token = 'e+6LVdVjQ57uSti1vScVBWPv6LfPlI+TmqyYIObsV9c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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