SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8ed2685e250ea9bcec208a00803b6f539924ead515eac14b12b6909727b32336' 
  AND token = 'KOd6Q8oGLpbvuPH/BbALuGH7mtinh1R2AeuftxmxAco=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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