SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b043108abdcb2a08c5e2e7e06b68d4fde6d470686b4929862801534b7744fb75' 
  AND token = 'bdUHHBMN9sCAbnhTqBamA9Gjf/LXG/3BpKUr59+bmzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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