SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '37a76ec2f8d825cc2d9a66d16dbe9e25e9f912c54b8c36a81c90dd0f3375a558' 
  AND token = '5t/PrW92KfBMDJZRNmJ7kiheLPCwrYSWc4lZD9RR0AA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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