SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '206bac47f8e35354c644cc1e0b6bb38694e3f363151551018170d96b3af94498' 
  AND token = 'HCMawCGDOrkx5A0hw6kg5+w+SpENBNhHwGEn2vp20jU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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