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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87f747870b39e2185143b00879c36675103633bc99373a3777fba37a46caaae4' 
  AND token = '90hXpCocHoUW1pHvXdbb+hz2+WXLHpesJdT8m5zE9EI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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