SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7bf6e6da40dc1dd6d49f39e532a541b6f249ca0c46a16b8377788e65b3f44d47' 
  AND token = 'DM4SkKfcY+ZgHvQW5As/7q1A9+4ZuNGUCEUWubKziaE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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